Many copiers, facsimile apparatus, printers, and similar electrostatographic image forming devices include a replaceable or refillable material supply module. The material supply module is typically connected to a device via a drive shaft and gear shaft coupling arrangement, which generally includes a drive shaft integral to the module that interacts with a gear shaft integral to the particular device.
FIG. 1 shows a drive shaft and gear shaft coupling arrangement 20, which is currently used in the material supply module of copiers, facsimile apparatus, printers, and similar electrostatographic image forming devices. A drive gear 22 drives a driveshaft cylinder 24 of a drive shaft 25. Drive gear 22 includes a gear shaft 26 at its center and an outside edge 28 having gear teeth. Gear shaft 26 has a front surface 30, which includes a twisted triangular coupling hole 32 having defined vertices 33 formed therein. Driveshaft cylinder 24 is fixedly mounted with a cylinder flange 34, which includes an axially outwardly extending concentric shaft 36 and an outside edge 38 having gear teeth. Concentric shaft 36 includes an axially outwardly twisted, triangular coupling member 40, which is axially raised from an outer surface 42 of the shaft for coupling to twisted triangular coupling hole 32 on gear shaft 26 of drive gear 22.
During the life of a device, driveshaft cylinder 24 and drive shaft 25 may be replaced one or more times depending on the frequency of use. Cylinder flange 34 is typically replaced when driveshaft cylinder 24 and drive shaft 25 are replaced. Because twisted triangular coupling member 40 of cylinder flange 34 generally twists in one direction and its torque forces are adjacent its axis of rotation, its fabrication is both complicated and expensive. In addition, because the torque forces acting on twisted triangular coupling member 40 of cylinder flange 34 are adjacent its axis of rotation, the member encounters high stresses.